The present invention relates to a method, particularly suitable for granular materials, of metering and additioning a material with great precision.
In the plastics materials processing, or treatment, industry the need is increasingly felt to add small or very small amounts of one or more specified additives such as dyes, foaming agents, lubricating agents and the like to a given mixture, also referred to as a batch, already prepared and bound to be subjected to processing, or treatment.
In treatment processes, where the hourly throughput of mixture of plastics granular material to be processed, or treated, is relatively low, the percentage amounts of additive to be added to the mixture before the treatment process can turn out to be very small, if not negligible.
Thus, the need arises for metering and/or additioning means that, besides providing for small and very small set amounts of granular material to be added, also provides for consistency in the set amounts of additive to be achieved with time.
It has already been proposed in the prior art the use of gravimetric metering devices that are suitable (usually by being set through a control keyboard) for metering a desired amount by weight of granular material. A gravimetric metering device is suitable for metering e.g. a 500 g batch or charge of granular material approximately every 20 seconds.